A common system for distributing television signals is known as a cable television system. Cable television systems distribute television channels over coaxial cable networks laid out between a cable broadcasting facility and a cable customer's house or building. With the advent of fiber optics, fiber optic cable is also used for the cable television network which exists between the cable broadcasting facility and a customer's home.
Regardless of whether the cable signal is distributed over fiber optic cable or coaxial cable, when the cable hook-up is made at a customer's home, coaxial cable is currently used to distribute the cable television signal throughout a customer's house. In structures built before the advent of cable television and coaxial cable usage, there is no existing cabling in the structure. If cable television is desired, it is necessary to wire each room in the building where a television set is to be used. As pointed out in Applicant's co-pending applications, this requires running new coaxial cable to each room where a television set is to be used and may involve draping cable over the outside walls of the house and drilling through the walls or the window frames of each room to run the cable. In order to provide multiple outlets in a particular room, it is necessary to split the cable and snake the cable through the walls or ceiling or along the baseboards to the desired locations. These requirements can be expensive, unsightly, and cause a degree of damage to the external and internal walls of the building.
Even in new construction, coaxial cable wiring has its disadvantages. The new construction may be "under wired" by not running cable to every room in the building where a television set will ultimately be used. Further, there may be only one cable television outlet installed per room. If a user's ultimate layout of a room does not include a television on the wall where the cable television outlet is located, it is necessary to run a cable wire from the outlet to the location of the television set.
With the increasing number of stations available through cable television, users may require and/or desire access to all of the available stations. In the current cable television systems, all cable television channels are broadcast throughout the house over the coaxial cable. As the number of available channels approaches into the hundreds, the present system becomes unworkable as there is a limit of approximately 100 channels (of programming) which can be simultaneously broadcast over conventional coaxial cable in an uncompressed analog format. This results in a limitation of present cable distribution systems within a house or other structure.
Another limitation of present cable systems relates to the Pay Per View channels. Pay Per View channels require a user to communicate the channel which the user desires to view to the cable television broadcasting facility. The cable television broadcasting facility then sends a signal to the user's cable selector box, allowing the signal for the requested channel to be viewed.
Selecting a Pay Per View channel incurs an additional cost for the user above the normal cable charges. Pay Per View programs are typically selected by tuning to a particular Pay Per View channel on the user's cable selector which is provided by the cable company. The cable selector box is connected to a telephone outlet in the user's house (in addition to the connection to the cable line). A call is made over the user's telephone line to the cable company through the selector box and the user's account is accordingly noted and debited. The use of Pay Per View in current cable systems requires a telephone outlet in proximity to the cable selector box to connect to the cable selector box in order to allow Pay Per View selection. This multiplies the problem of cable outlets by requiring that not only does every room require a cable outlet in a location convenient for installation of a television, but now requires a telephone outlet in every room. This telephone outlet must also be in proximity to the cable television selector in order to make a connection. The further a telephone outlet is located from the cable television selector box, the longer and more noticeable will be the telephone wiring running between the telephone outlet and cable selector box.
Goodman (U.S. Pat. No. 5,010,399) discloses a video transmission and control system utilizing internal telephone lines to distribute a television signal. One of the limitations of Goodman is that in order to simultaneously transmit more than one video/television signal, it is necessary to tune the receiver/selector of Goodman to an alternate VHF channel. For example, if a first receiver/selector is operating on VHF channel 3 or 4 as is common in video communication devices connected to television sets such as cable convertors, VCRs, and laser disc players), a second television selector/receiver is required to operate at a different VHF channel such as channel 5 or 6. As it is not unusual to have more than two television sets operating in a home or building, it is necessary to move upward in the VHF channels to allow additional television sets. Such a system increases the chance of interference from broadcast stations as more channels are used, particularly in overlapping broadcast regimes in urban areas.
Accordingly, it is desirable to be able to operate multiple, inadequate television sets simultaneously within a home or building without the need for coaxial cable. It is also desirable to allow selection of cable television channels or alternate video sources using a device which interfaces with the television on VHF channel 3 or 4 for each of the multiple, independent and simultaneous televisions used.